Zora had posed the same question as Septimus and he had answered it.

But her faith in the Cure itself, his mission to spread it far and wide over the earth, and to save the nations from vulgar competitors who thought of nothing but sordid gain--that, he felt sure, remained unshaken.
Yet as he walked along, in the alien though familiar city, he was smitten, as with physical pain, by a craving for her presence, for the gleam of her eyes, for the greatness of sympathy and comprehension that inhabited her generous and beautiful frame.

The need of her was imperious.

He stopped at a cafe on the Boulevard Saint-Michel, called for the wherewithal to write, and like a poet in the fine frenzy of inspiration, poured out his soul to her over the heels of the armies of the world.
He had walked a great deal during the day.

When he stepped out of the cab that evening at the Gare de Lyon, he felt an unfamiliar stinging in his heel.